Abstract

Tritium/SHe-, 14C-and helium/neon data from a station locatedi n the central Nansen Basin of the Arctic Oceana rereported and discussed. It. is demonstrated that 3He is a valuable tracer
for studies of the upper water column and, together with tritium, 3He provides a rough time scale of the ventilation of these waters. The apparent tritium/3He age is about 7 years in the surface water and about 14 years in the lower part of the halocline. Water of Atlantic origin defined by a temperature maximums shows tritium/3He ages between 7 and 9 years. This variation of ages indicates that the circulation of the individual water layers of the upper water column is largely decoupled and occurs on different time scales.Tritium/3He age sobserved in the Arctic Intermediate Water suggest a ventilation on a time scale of 15 to 20 years( depth. <1000 m). The mean age of the Eurasian Basin Bottom Water is estimated on the basis of 14 C data to
approximately 200 to 250 years. There is no indication of noble gas fractionation due to sea ice formation below the surface layer. From analysis of the 3He background it appears that there is a small primordial 3 He componenitn Eurasian Basin Bottom Water.